Update: iRiver has a new e-reader too, and it too sports a high-resolution display. iRiver says that the Story HD is the highest-resolution 6" E Ink e-reader.
Hanvon have announced a new 9.7" e-reader, the WISEreader E920. They say that it is the first one to use a new E Ink display offering 200dpi - the highest resolution e-reader display yet. Check out this photo showing how the compares to a regular E Ink display: